Mathematical Problems in Engineering

https://www.hindawi.com/journals/mpe/

List of Papers (Total 806)

A Deep Learning Prediction Model Based on Extreme-Point Symmetric Mode Decomposition and Cluster Analysis

Aiming at the irregularity of nonlinear signal and its predicting difficulty, a deep learning prediction model based on extreme-point symmetric mode decomposition (ESMD) and clustering analysis is proposed. Firstly, the original data is decomposed by ESMD to obtain the finite number of intrinsic mode functions (IMFs) and residuals. Secondly, the fuzzy -means is used to cluster...

Task Space Trajectory Tracking Control of Robot Manipulators with Uncertain Kinematics and Dynamics

To improve the tracking precision of robot manipulators’ end-effector with uncertain kinematics and dynamics in the task space, a new control method is proposed. The controller is based on time delay estimation and combines with the nonsingular terminal sliding mode (NTSM) and adaptive fuzzy logic control scheme. Kinematic parameters are not exactly required with the...

A Complex Variable Solution for Rectangle Pipe Jacking in Elastic Half-Plane

In mechanics, the solution of soil stresses and displacements field caused by shallow rectangular jacking pipe construction can be simplified as half-plane problem. Both the boundary conditions of the surface and the cavity boundary must be taken into account. It is the essential prerequisite for mechanical analysis of the pipe jacking with the complex variable theory that the...

Cracking Behavior of a Concrete Arch Dam with Weak Upper Abutment

The cracking behavior and failure mode of a 78 m high concrete double-curvature arch dam with weak upper abutment are investigated through performing cracking analysis. The mechanical behavior of concrete is simulated using a smeared crack model, in which a combination of the compression yield surface and the crack detection surface with a damaged elasticity concept is employed...

Fuzzy Supervisor Approach Design Based-Switching Controller for Pumping Station: Experimental Validation

This paper proposes a discrete-time switching controller strategy for a hydraulic process pumping station. The proposed solution leads to improving control system performances with two tests: combination of Fuzzy-PD and PI controllers and Fuzzy-PID and PI controllers. The proposed design methodology is based on accurate model for pumping station (PS), which is developed in...

Thermoelastic Analysis for Two Collinear Cracks in an Orthotropic Solid Disturbed by Antisymmetrical Linear Heat Flow

The problem of two collinear cracks in an orthotropic solid under antisymmetrical linear heat flow is investigated. It is assumed that there exists thermal resistance to heat conduction through the crack region. Applying the Fourier transform, the thermal coupling partial differential equations are transformed to dual integral equations and then to singular integral equations...

Revisiting the Low-Frequency Dipolar Perturbation by an Impenetrable Ellipsoid in a Conductive Surrounding

This contribution deals with the scattering by a metallic ellipsoidal target, embedded in a homogeneous conductive medium, which is stimulated when a 3D time-harmonic magnetic dipole is operating at the low-frequency realm. The incident, the scattered, and the total three-dimensional electromagnetic fields, which satisfy Maxwell’s equations, yield low-frequency expansions in...

Research on Control Strategy of AC-DC-AC Substation Based on Modular Multilevel Converter

Significant disadvantages in power quality especially the unbalance problem and neutral sections restrict the evolution of conventional traction power supply system. A new traction power supply system based on three-phase to single-phase converter is studied, which can transfer active power from three-phase grid to single-phase catenary. One catenary section could be utilized in...

Extended VIKOR Method for Intuitionistic Fuzzy Multiattribute Decision-Making Based on a New Distance Measure

An intuitionistic fuzzy VIKOR (IF-VIKOR) method is proposed based on a new distance measure considering the waver of intuitionistic fuzzy information. The method aggregates all individual decision-makers’ assessment information based on intuitionistic fuzzy weighted averaging operator (IFWA), determines the weights of decision-makers and attributes objectively using...

Supplier Selection by Coupling-Attribute Combinatorial Analysis

Increasing reliance on outsourcing has made supplier selection a critical success factor for a supply chain/network. In addition to cost, the synergy among product components and supplier selection criteria should be considered holistically during the supplier selection process. This paper shows this synergy using coupled-attribute analysis. The key coupling attributes, including...

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Using the method of multiple scales and perturbation method, a set of coupled models describing the envelope Rossby solitary waves in ()-dimensional condition are obtained, also can be called coupled NLS (CNLS) equations. Following this, based on trial function method, the solutions of the NLS equation are deduced. Moreover, the modulation instability of coupled envelope Rossby...

Output Feedback Finite-Time Stabilization of Systems Subject to Hölder Disturbances via Continuous Fractional Sliding Modes

The problem of designing a continuous control to guarantee finite-time tracking based on output feedback for a system subject to a Hölder disturbance has remained elusive. The main difficulty stems from the fact that such disturbance stands for a function that is continuous but not necessarily differentiable in any integer-order sense, yet it is fractional-order differentiable...

Experimental and Analytical Study of Slender Reinforced Concrete Shear Wall under Cyclic In-Plane Lateral Load

This study describes a slender reinforced concrete shear wall experimental test under in-plane cyclic lateral load, and the development of an analytical model which uses the fiber method approach to consider hysteretic nonlinear constitutive material models behavior. The shear wall tested had bending behavior, since the amount of longitudinal reinforcing bars produced weak...

A Feeding Strategy in Inner L-Shape Ring Hot Rolling Process

In order to make the inner L-shape ring polling process with a closed die structure (ILRRCDS) on the top and bottom of the driven roll stable, at first, this paper established the mathematical model for ILRRCDS. Then, the plastic penetration and biting-in conditions for ILRRCDS were deduced based on plain ring rolling theory. Moreover, a feeding strategy that can realize a...

Enhancing the Performance of Biogeography-Based Optimization Using Multitopology and Quantitative Orthogonal Learning

Two defects of biogeography-based optimization (BBO) are found out by analyzing the characteristics of its dominant migration operator. One is that, due to global topology and direct-copying migration strategy, information in several good-quality habitats tends to be copied to the whole habitats rapidly, which would lead to premature convergence. The other is that the generated...

A Mathematical Programming Approach to Brand Efficiency of Smartphones in the US Market

This study applied mathematical programming approach to investigate the brand efficiency of smartphone brands by collecting data of 2013–2015 from Consumer Report. The brand efficiency was completed by employing the slack-based measure in data envelopment analysis. The degree of inefficiency of each brand was evaluated, and each brand’s metatechnology ratio was calculated using...

Supplier’s Joint Investments in Cost Reduction and Quality Improvement in a Decentralized Supply Chain

We consider a decentralized supply chain with a downstream manufacturer and an upstream supplier. The upstream supplier sells a product to the manufacturer, who faces a quality and price sensitive demand. The supplier has a chance to invest in both cost reduction and quality improvement of its product. We derive the optimal investment and pricing decisions for the supply chain...

Numerical Study for Near-Bed Variables in Velocity-Skewed Oscillatory Sheet Flow Transport

The near-bed sediment concentration and vertical sediment flux are important in sediment transport mechanics, but they are known much less than the horizontal sediment flux, especially for fine sediment in unsteady flows. A developed two-phase model is applied to study the near-bed sediment concentration, vertical sediment flux, and the relevant total sediment amount for the...

Comprehensive Numerical Investigations of Unsteady Internal Flows and Cavitation Characteristics in Double-Suction Centrifugal Pump

The RNG k- turbulence model combined with cavitation model was used to simulate unsteady cavitating flows inside a double-suction centrifugal pump under different flow rate conditions based on hexahedral structured grid. The numerical external characteristic performances agree well with the experimental performances. The predicted results show that the turbulence kinetic energy...

Parallel Multiprojection Preconditioned Methods Based on Subspace Compression

During the last decades, the continuous expansion of supercomputing infrastructures necessitates the design of scalable and robust parallel numerical methods for solving large sparse linear systems. A new approach for the additive projection parallel preconditioned iterative method based on semiaggregation and a subspace compression technique, for general sparse linear systems...

Prediction of Frost-Heaving Behavior of Saline Soil in Western Jilin Province, China, by Neural Network Methods

In this study, backpropagation neural network (BPNN) and generalized regression neural network (GRNN) approaches are used to predict the frost-heaving ratio (FR) of the saline soil specimen collected from Nong’an, Western Jilin, China. Four variables, namely, water content (WC), compactness, temperature, and content of soluble salts (CSS), are considered in predicting FR. A total...

Research on NDT Technology in Inference of Steel Member Strength Based on Macro/Micro Model

In consideration of correlations among hardness, chemical composition, grain size, and strength of carbon steel, a new nondestructive testing technology (NDT) of inferring the carbon steel strength was explored. First, the hardness test, chemical composition analysis, and metallographic analysis of 162 low-carbon steel samples were conducted. Second, the following works were...

Design of Thermal Barrier Coatings Thickness for Gas Turbine Blade Based on Finite Element Analysis

Thermal barrier coatings (TBCs) are deposited on the turbine blade to reduce the temperature of underlying substrate, as well as providing protection against the oxidation and hot corrosion from high temperature gas. Optimal ceramic top-coat thickness distribution on the blade can improve the performance and efficiency of the coatings. Design of the coatings thickness is a...

A Modified Floor Field Model and Pareto Optimum of Pedestrian Evacuation Efficiency

A modified floor field model is proposed to simulate the pedestrian evacuation behavior in a room with multiple exits. The modification relies upon introduction of a so-called semidynamical floor field which additionally embodies two cognition coefficients related to exit width and pedestrian distribution around exits. The energy consumption and time requirement of evacuees are...